Methods of this kind are known. They in particular serve to be able to prevent collisions with pedestrians in road traffic or, optionally, still to be able to take suitable safety measures in good time.
It is known to recognize obstacles with the help of sensors, e.g. acceleration sensors and/or contact sensors, which are arranged in the region of a bumper of a motor vehicle. However, sensors of this type permit recognition of obstacles only when they are in the direct proximity of the vehicle or when a collision has already taken place.
The use of cameras in motor vehicles is also generally known, for example to image the environment of the motor vehicle on a display visible to the driver of the motor vehicle as a parking aid.
Generally, however, the amount of the image data to be processed and the automatic evaluation of the generated images have proven to be problematic with the use of cameras. This applies in particular when the evaluation of the image material not only has to take place automatically, but also particularly fast, such as is required, for example, in a vehicle safety system for the protection of persons on a collision with the motor vehicle.
A method is already known from EP 1 646 008 A1 for the recognition of an obstacle, in particular a person, located in a path of travel of a motor vehicle, wherein a first image and, spaced apart in time therefrom, a second image is taken of the environment of the motor vehicle in the direction of travel by means of a camera; a first transformed image is generated by projection of the first image taken from the plane of the camera into the plane of the ground and a second transformed image is generated by projection of the second image taken from the image plane of the camera into the plane of the ground; a difference image is determined from the first and second transformed images, and it is determined by evaluation of the difference image whether an obstacle is located in the path of travel of the vehicle.
This known apparatus has proven itself in practice. However, due to the geometrical conditions here, only obstacles or parts of obstacles above the ground plane can be detected which lie below the horizon. In a number of cases, however, one would like to detect the total contour, that is both the part of the obstacle lying below the horizon and the part of the obstacle lying above the horizon, to ensure a more reliable detection of the obstacle.